CVE-2019-17016

Mozilla: Bypass of @namespace CSS sanitization during pasting

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Severity

Important

Red Hat Product Security

6.1

CVSS 3.1

Review impact separately from score.

Published · January 7, 2020

Updated · November 22, 2025

Description

When pasting a <style> tag from the clipboard into a rich text editor, the CSS sanitizer incorrectly rewrites a @namespace rule. This could allow for injection into certain types of websites resulting in data exfiltration. This vulnerability affects Firefox ESR < 68.4 and Firefox < 72.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')